Illuminating prism structure.



No. 720,386. PAT'RNTRD RRR. 1o, '1903.

P. L. o. WARSWORTR. ILLUMINATING PRISM STRUCTURE.

i APPLICATION FILED JULY 12., 1900.

I0 MODEL.

INVENTOR vl maar.

WITNES'SES:

UNITED STATES @PATENT OFFICE.

FRANK L. O. VADSVORTIAI, OF ALLEGHENY, PENNSYLVANIA, ASSIGNOR TO PRESSED PRISM PLATE GLASS COMPANY, A CORPORATION OF WEST VIRGINIA.

ILLUMINATING PRISM STRUCTURE.

SPECIFICATION forming part of Letters Patent No. 720,386, dated February 10, 1903.

Application led July 12, 1900.

Serial No. 23,315. (No model.)

To all whom. it may concern: apartment, these surfaces t t may be curved, o

Be it known that I, FRANK L. O. WADS- so as to disperse the bundle of rays 1LL la, as WORTH, of Allegheny, in the county of Alleat lb lc. A further object of thus curving the gheny and State of Pennsylvania, have insurfaces in the case of such structures as 5 vented a new and useful Improvement'. in those shown in Fig. lis to enable the emer- Illuminating Prism Structures, of which the gent bundles of rays to pass the points of the following is a full, clear, and exact descripintermediate prisms P' P', which are placed tion, reference being had to the accompanyon the emergent side between the surfaces it ing drawings, forming part of this speciticafor the purpose, as already stated, of receiv- Io tion, in whiching'anddirecting into the room rays of light Figure l represents in cross-section a porfrom a secondary direction. Part of these 6o tion of my improved form of structure, and rays, such as 2 2, fall rst on the surfacess s Figs. 2, 3, 4L, and 5 represent modifications. of the prisms P on the front of the structure The object of my invention is to obtain an andare there refracted in the direction 2L 2fL r 5 improved illuminating structure which will and received on the faces w of the prisms P',

efficiently utilize the light incident upon it whence they are reected to the face u. of these from two or more directions, as the conditions same prisms and thence pass into the room in under which illuminating structures are used the direction 2b, parallel to the general direcfrequently require that light received from tion la of the primary rays. Another part of 2o two or more different sources of illumination 'these rays, such as 2' 2', after refraction at the on the outside shall be directed in substanfaces s sfall upon the surfaces r of the prisms 7o tially the same direction into the space to be P, are reflected thereby in the direction 2C, illuminated. In my improved construction meet the surfaces u of the prisms P', are rethis is accomplished by providing the strucected thereby through the faces w in the di- 25 ture with a series of prisms on the front or rections 2d, fall upon the prism elements P' incident side which are so designed as to rejust below, and are by them turned back by ceive the light from the principal source of refraction through the body of the prism-plate illumination and deiect it in the required diin the direction 2e, finally emerge from the rection through a series of substantially parfront of the same,and falling upon the prisms 3o allel dioptical surfaces on the emergent side P on this side are again turned back, first by and at the same time to receive the rays from refraction and then by reflection, at one of 8o the secondary source of illumination and dithe faces fr of said prisms, so as to finally rect them at an angle upon a second series of emerge through one of the faces ton the rear prisms on the emergent side, by which they side of the structure in directions 2f, sub- 3 5 are deflected into the room in a direction substantially parallel to the directions 1a 2b of stantially parallel to that taken by the iirst the preceding sets of rays. 8 5 set of rays. Thus in Fig. l the rays l l l, In the modifications shown in Fig. 2 the refalling upon the receiving sides s s of the lations and actions of the two sets of prisms prisms P P, are refracted thereat to the faces P P P P' and of the intermediate surfaces tt 4o fr r of the same prisms, from which they are are similar, the only difference being that in reected toward the emergent side of the this case the surfaces r of the prisms P are 9o plate, as at l l, and there fall upon surcurved, so that the bundles of rays directed faces z5 t, which in general outline and positherefrom from the principal direction are tion are substantially parallel to the general converged, as at 1 lf2 The advantage of this 45 plane of the structure and which therefore arrangement in certain cases is that a smaller transmit these rays without substantial area of emergent surface t t is necessary for change of direction. When a certain disperthe transmission of the entire body of these sion of the rays behind the structure is derays, and the prisms P' may therefore be sired in order to more fully illuminate the larger than in the preceding case, and thus receive a larger proportional part of the rays from the secondary direction 2 directly upon the faces w w. In Fig. 3 a similar arrangement of parts is shown; but in this case the receiving-faces s s of the prisms P are curved, and as a result both the rays from the direction l and from the direction 2 are converged when they strike the surface. As before, rays from the direction l are reiiected directly at the surface r in a convergent bundle toward the rear of the prism-plate and pass through the surfaces t t, which may be either flat, as at A A, or concave, as at'B B, Fig. 3. The rays from the secondary direction 2 2 are refracted at s, pass in converging bundles to the surfaces w of the prisms P, and are thence reliected as before into the room in the direction 2b 2c.

In the case of such structures as those shown in Figs. 2 and 3 the faces of the prisms P may have any curvatures desired. In most cases the best results will be secured, as pointed out more fully in my applications Serial Nos. 687,134 and 687,132, when the faces r coincide in cross-section with portions of parabolic curves and the surfaces s coincide in cross-section with portions of hyperbolic curves, as at c o', Fig. 3. In some cases I may also make one or both faces of the prisms P/ Pl curved, as in Fig. 4, the object and result of this being also to disperse the bundles of secondary rays deflected by these prisms, as at 2" 2C. In other cases the prisms on the emergent side may be refracting in character, as in the modication illustrated in Fig. 5, in which the bundles of secondary rays from the direction 2 2 after refraction at the faces s s of the prisms P P are received on the faces w w of the second set of prisms at such an angle as to be refracted thereat into the space behind the plate in the required direction 21". The rays of light from the principal direction l l are after deflection at the faces 'r fr of the prisms P P received as before on intermediate dispersing-surfaces ft and thence transmitted in the directions lb 1c. The intermediate surfaces t t may be fiat, as shown in Fig. 2 and at A A in Fig. 3, convexly curved, as in Fig. l, or concavely curved, as in Figs. 3 and 5. In all these cases they act as dispersing-surfaces-z'- e., they alter the angular divergence or convergence of the bundles of rays which fall upon them. In the first two cases this occurs because the bundles of rays falling upon these surfaces are convergent, in the last two cases because the surfaces themselves are curved. I therefore designate these surfaces by the general term dispersing-surfaces.

In laying off the surfaces of the structure so as to utilize most fully the rays from both the principal and secondary directions I iirst lay off the prisms P on the front side of the structure with the surfaces s s preferably nearlyperpendicular to the direction l 1 of the principal incident rays and with surfaces r r at such an angle that these rays are reliected in the required direction la. I next determine the direction 2LL which the rays 2 take on refraction at the surfaces S and then locate the general plane T T of the surfaces t t so that the largest possible proportion of the rays 2n may be received by the prisms P intermediate between the surfaces z5 t. This will in general be the case when the lower edges of the facest t meet the upper edges of the prism-faces u. u at the points of intersection of the lower rays of the bundles from the direction l l with the upperrays of the bundles from the direction 2 2. I then lay off the surfaces u and w of the prisms P so as to transmit the rays 2 in the direction 2b.

In building up these structures the plate may be made either in one integral piece, as in Figs. 2, 4, and 5, or in two parts M Q, as in Figs. 1 and 3. In the latter construction the plates may be cemented together with transparent cement or iiux or may be separated slightly and the intervening space filled with liquid of substantially the same index of refraction as the glass itself, as in Fig. 3. In this last case the two plates may be mounted, as in Fig. 3, so as to be movable one with respect fo the other, thus enabling me by adjusting one longitudinally to regulate at will the amount of light sent in agiven direction. This general means of regulation I do not here claim broadly, as it is made the subject of another application for Letters Patent, Serial No. 694,828.

Without limiting myself to the specific forms orconstructions herein shown,I claiml. An illuminating structure having on one side a series of prisms and on the other a second series of prisms parallel to the first, and a series of dispersing-surfaces arranged between the prisms; substantially as described.

2. An illuminating structure having on the first or receiving side a series of prisms, and on the discharging side a second series of smaller prisms parallel to the first and separated by a series of dispersing-surfaces; substantially as described.

3. An illuminating structure having on the first or receiving side a series of prisms substantially parallel to the general plane ofthe structure, and on the discharging side a second series of smaller prisms parallel to the first and separated by a series of dispersingsurfaces; substantially as described.

4. An illuminating structure having on one side a series of prisms with receiving and deflecting sides, and on the other a composite discharging-surface consisting of a series of dispersing-surfaces transversely opposite the deiiecting sides of the iirst prisms and placed alternately with relation to a series of smaller prisms; substantially as described.

5. An illuminating structure having on one IOO IIO

side a series of prisms and on the other side In testimony whereof I have hereunto set a second series of prisms parallel to the first, my hand.

and a series of dispersing-surfaces arranged i between the prisms, with means for moving F L' o WADSWORTH' the second series of prisms and dispersing- Witnesses:

surfaces with reference to the irst; substen- L. A. CONNER, J r.,

tielly as described. GEO. B. BLEMING. 

